Silicon oxide films prepared by low pressure chemical vapor deposition (LPCVD) are used in the fabrication of integrated circuits and also in the fabrication of multi-layer optical filters. It is often desirable and necessary to form such deposits at relatively low temperatures, either to avoid damaging thermally sensitive structures already present on the deposition substrate or because of process temperature constraints imposed by the need to deposit efficiently one or more materials within the same reactor environment. This latter case is particularly relevant during the deposition of multi-layer optical filters. In this context, process temperatures below approximately 500.degree. C. and, more typically, below approximately 450.degree. C. are considered to be low temperature.
One approach to achieving low deposition temperatures has been to employ non-thermal chemical activation means to cause various gas-phase deposition precursors to react at lower temperatures than would otherwise be the case. Examples of this approach include so-called plasma-enhanced chemical vapor deposition (PECVD), and photo-assisted chemical vapor deposition (PACVD) in which an exposure to a glow discharge or high energy electromagnetic radiation are employed as the activating means either prior to the deposition or simultaneously with the deposition.
Yet another approach involves the use of chemical vapor deposition precursors which thermally decompose to SiO.sub.2 at lower temperatures than do more commonly used precursors such as tetraethyl-orthosilicate (TEOS). Included in the class of low temperature deposition precursors are alkylsilanes and alkoxysilanes. In particular, the use of the alkoxysilane diacetoxyditertiary-butoxysilane (DADBS) as a low temperature chemical vapor deposition precursor has been the subject of much study in recent years. Despite extensive research, low temperature SiO.sub.2 deposition from DADBS is unacceptably slow, typically being on the order of approximately 10-20 .ANG. per minute in an LPCVD reactor operating at approximately 450.degree. C.
Thus, a need exists for a method to substantially enhance the low temperature deposition rate of SiO.sub.2 from DADBS. Furthermore, a need exists for an enhanced deposition method that may achieve satisfactory deposition rates without the use of plasma, photon, or any other extraordinary activation techniques which increases both the cost and complexity of the overall process.